docs: def encrypt_document(self, document_id, content, threshold=0):
          """
          encrypt string data using the DID as an secret store id,
          if secret store is enabled then return the result from secret store encryption
  
          None for no encryption performed
  
          :param document_id: hex str id of document to use for encryption session
          :param content: str to be encrypted
          :param threshold: int
          :return:
              None -- if encryption failed
              hex str -- the encrypted document
          """
          return self._secret_store_client(self._account).publish_document(
              remove_0x_prefix(document_id), content, threshold
          )